Crossfit has gotten tremendously popular and thus a lot of people (personal trainers) are trying to cash in on it.

I don't think most people need a personal trainer. In terms of crossfit the only thing I'd pay for is some instruction in how to do the olympic lifts using a barbell (and I'd probably be happier to join a weightlifting team/coach to learn this than someone who got a crossfit certification). However, I'd probably just skip those WODs (since they appear to be chosen at random anyway) and use the KB lifts instead.

Creating a crossfit home gym can cost you anything from a very little to a few thousand for olympic standard weights and platforms. This is where I like the KB. It costs much less and takes up far less space.

Crossfit.com posts the workout of the day don't they? I've thought of just copying that rather than paying to join a pricey gym (like JD on GRS does) - the only downside is maybe not having all the equipment.

Although, we have a local gym that only charges $10/month, that is tempting.

Only join a gym if you need instruction in Olympic technique (which some instructors might not have down pat anyway) and don't want to substitute KB lifts OR you need a personal trainer to motivate you at $100+/month.

IMHO it's a fairly steep price to pay considering that some WODs are "run 5k" or "do 100 pull ups followed by 200 push ups followed by 300 squats".